How Does a Placebo Really Work?

The placebo effect is particularly strong in individuals with some psychiatric illnesses or with medical conditions affected by emotional distress (e.g., headache, irritable bowel syndrome). However, there has been little systematic research in this area. In this elegantly designed study, researchers examined three putative components of the placebo effect in 262 patients with irritable bowel syndrome diagnosed by the Rome II criteria.

Patients were randomized to receive simple assessment and observation (wait list), placebo intervention (sham acupuncture given twice weekly for 3 weeks with very limited human interaction), or augmented patient–provider relationship (placebo intervention plus an enhanced relationship with the provider, involv…